Why we need better tests for Parkinson’s

Medical tests are a vital part of modern medicine. They help us understand what’s going on inside our bodies and then identify and test the right approaches to fix the underlying problems. Here are some examples:

• blood tests to check cholesterol levels
• biopsies to look for signs of cancer
• x-rays to find broken bones
• and many others.

What all these medical tests have in common is that they can detect a biological change inside the body. These biological changes are referred to as ‘biomarkers’. These tests give doctors important information to help them detect changes, diagnose conditions, and treat people.

It’s no coincidence that in conditions where we have good biomarkers and medical tests, we tend to make faster scientific progress.

HIV is an example of a medical testing success story.

In the 1990s, new tests were developed to measure the presence and level of HIV in blood samples. This gave researchers and doctors the key to detecting HIV early, monitoring the progress of infection, and testing the effectiveness of new treatments.

Today blood tests are used to diagnose and treat people with HIV, and have played a vital role in developing treatments that stop the virus from replicating in the body.

Sadly, in conditions where we don’t have such good medical tests we have struggled to make the same progress. Parkinson’s has historically fallen into this category, lacking a clear way to diagnose and measure the progression of the condition as well as testing the effectiveness of new treatments. This is changing.

Why haven’t there been good medical tests for Parkinson’s?

Parkinson’s is a condition that primarily affects the brain, the most complicated and mysterious organ in our bodies. We know that dopamine-producing cells in the substantia nigra, a small but vital region in the centre of the brain, stop working properly and are lost gradually over time.

The current challenges:

• Brain scanning techniques, although helpful and continually improving, aren’t good enough to see what’s happening in brain cells to definitively diagnose or monitor the condition.
• We can’t take samples of cells from inside the brain to analyse as we can with other organs.

So scientists have turned their attention to looking to see whether it’s possible to detect and measure changes in the body outside of the brain, to give us useful information about Parkinson’s.

How could better tests accelerate research and transform treatment for Parkinson’s?

Early detection

Currently, people are diagnosed with Parkinson’s after a significant amount of dopamine-producing brain cells have been lost. Better tests could help us improve our understanding of the early stages of Parkinson’s, which currently is difficult to study. This could help identify people to take part in research looking at potential treatments to slow or stop the progression of the condition, where there’s the most chance of success.

Read one of our related blogs: Diagnosing Parkinson’s earlier: so what?

A definite diagnosis

There is no way of 100% confirming a Parkinson’s diagnosis. This unfortunately means the journey to diagnosis can be a long one and often means that around 1 in 5 people diagnosed with Parkinson’s might not actually have the condition.

Therefore we may currently be testing new drugs in people who don’t have the condition and are unlikely to benefit. Better tests will allow more certainty that the right people are trialling possible treatments which will lead to a better chance of success.

Choosing the right treatment

If someone is identified as having breast cancer, a sample of tissue is analysed to see exactly what kind of cancer they have before a treatment plan is decided. This personalised approach has made cancer treatment much more effective and one day we hope to see the same kind of approach in Parkinson’s.

It's thought that Parkinson’s might have differing underlying causes for different people. For some it might be the toxic waste clogging up their brain cells but for others, it might be the dysfunction of energy production. There's currently no way to test this. Better tests may allow for a more personalised treatment approach.

Monitoring Parkinson’s over time

Today, we don’t have any medical tests that can tell us how Parkinson’s is progressing and whether it’s getting worse and how quickly, or if it’s getting better. We rely on examining symptoms and asking patients how they feel. This doesn’t build a complete picture of someone’s condition, it just provides a snapshot that may not be representative. 

This is a big problem for clinical trials that are testing new treatments that aim to slow, stop or reverse Parkinson’s, as researchers struggle to tell whether these drugs are working or not.

How close are we to medical tests for Parkinson’s?

As you may have noticed, there is an increasing number of stories in the news about new tests for Parkinson’s, in a wide, and sometimes surprising, variety of ways.

Let’s take a look at some of the most exciting recent advances in this area.

This is not an exhaustive list and all of the tests discussed here are currently in research and development and are not yet in use as part of regular Parkinson’s treatment and care.

Lumbar puncture test

In April 2023, researchers funded by the Michael J. Fox Foundation announced the development of a new test that can identify abnormal alpha-synuclein, a protein known to be involved in most cases of Parkinson’s, in cerebrospinal fluid.

In their study, 93% of people with Parkinson’s who had the test were proven to have abnormal alpha-synuclein. The test also showed promise in detecting abnormal alpha-synuclein in those who were at high risk of developing Parkinson’s or had some early signs of the condition but had not yet been diagnosed.

This test represents a major step forward, as previously it’s only been possible to identify abnormal alpha-synuclein in post-mortem brain tissue samples.

The challenge of this test is that it requires a lumbar puncture, which involves a sample of fluid from the spinal column being taken for analysis.

And also, the test can only tell whether abnormal alpha-synuclein is present or not. It cannot yet be used to measure the levels of abnormal alpha-synuclein which could help monitor the progression of the condition.

Read more about the spinal fluid test on the Michael J. Fox Foundation website.

Blood Tests

There’s been a flurry of research looking at blood tests for Parkinson’s.

• In December 2023 research was published showing promise for a blood test to look at levels of alpha-synuclein found in small membrane bound packages in the blood called exosomes. The test was able to distinguish who was in a high risk or low risk group for developing Parkinson’s. Read more about the alpha-synuclein based blood test on our research news pages. 
• In August 2023 evidence was shared for a blood based test to detect a potential marker for Parkinson’s based on the damage to brain cell batteries called mitochondria. Read more about the mitochondrial based blood test research on our research news pages.
• June 2024 saw another research news story, enabled by Parkinson’s UK funding, showing promise for a blood based test for Parkinson’s. This study was based on multiple markers found in the blood and was able to predict Parkinson’s 7 years before movement symptoms appeared. Read more about the multiple panel blood test on our research news pages.

Further validation of these tests are ongoing before they can be used as a tool in the clinic. 

Eye scans

Now for something completely different. In 2023, researchers at Moorfields Eye Hospital in London used artificial intelligence to analyse eye scans from hundreds of thousands of people alongside healthcare records.

They were able to identify subtle changes in the retina that could detect Parkinson’s up to 7 years before diagnosis.

Data from eye scans has previously helped reveal signs of other neurodegenerative conditions, including Alzheimer’s and multiple sclerosis, and eye scans are already used to identify people at risk of high blood pressure and diabetes.

Definitely one to keep an 'eye' on! 

Read our news story about the study that used eye scans to detect Parkinson’s.

Skin swabs

Finally, in 2022 researchers at the University of Manchester announced the development of a test that could help diagnose Parkinson’s in 3 minutes using a simple skin swab.

The test looks for changes in the sebum: the oily layer that protects the skin. The research was inspired by Joy Milne, who discovered she could 'smell Parkinson’s' following her husband’s diagnosis at the age of 45.

Joy’s observation led to a Parkinson’s UK-funded study which suggested that there were chemical changes in the sebum between people with and without Parkinson’s.

Read our news story about the skin swab test that hopes to help Parkinson’s diagnosis.

Real progress, real hope

We’ve seen tremendous progress in the development of exciting new tests for Parkinson’s in the last year alone.

We are hopeful that these new tests will start being used within the next few years, first in research to improve clinical trials, and then in general care to improve diagnosis and treatment for everyone with Parkinson’s.

Tests have made a huge difference in other conditions, from cancer to HIV, and now it’s time for the same revolution in Parkinson’s.